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Anthropogenic activities in the environment have an impact on climate change. Among these activities is the use of the chainsaw which plays an important role through releasing greenhouse gas emissions in the atmosphere. Hence the need for research on improved logging operations is of importance. The present study compares carbon monoxide (CΟ) and nitrogen dioxide (NO 2) emissions generated by the engines of one catalytic chainsaw and two conventional chainsaws, of which one is professional and the other amateur. Measurements were carried out under three functional modes (infrequent accelerator use, use of quality oils, use of clean filters). Measurements that were conducted under normal conditions were named "witness measurements" and were used for future comparisons. Additionally, a set of measurements for CΟ and ΝΟ 2 emissions was collected under different operation modes for all three types of saws (frequent accelerator use, use of low quality oils, use of impure filters). Data collection was carried out in real conditions using a portable gas detector. Average concentration values of CΟ and ΝΟ 2 under normal conditions for all three types of chainsaw found in the air of the operator"s breathing zone were 88.32 ppm and 0.07 ppm respectively. Results show that CO concentrations exceed the permissible exposure limit (50 ppm), whereas CO concentrations in excess of the short-term exposure limit (300 ppm) were only found in the case of the amateur chainsaw operated with low quality oils. These results are of use towards efforts to reduce the CO and NO 2 to the atmosphere.
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This is a pre-print of a paper accepted for publication in International Journal of
Forest Engineering
Research of Exhaust Emissions by Chainsaws with the use of a Portable
Emission Measurement System
Vasiliki Dimou1*, Apostolos Kantartzis2*, Chrisovalantis Malesios3,4 and Emmanouil
Kasampalis5*
1Laboratory of Forest Technology, 2Laboratory of Forest Engineering Sciences and
Surveying, *Democritus University of Thrace, Department of Forestry and Management of
the Environment and Natural Resources, 193 Pandazidou Orestiada, PC 68200, Greece
3Department of the Environment, University of the Aegean, Mytilene PC 81100, Greece,
4Aston Business School, Aston University, Birmingham PC B4 7ET, UK,
vdimou@fmenr.duth.gr1, apkantar@fmenr.duth.gr2, malesios@env.aegean.gr3,
c.malesios@aston.ac.uk4, manoliskas98@gmail.com5
Abstract
Anthropogenic activities in the environment have an impact on climate change.
Among these activities is the use of the chainsaw which plays an important role
through releasing greenhouse gas emissions in the atmosphere. Hence the need for
research on improved logging operations is of importance. The present study
compares carbon monoxide (CΟ) and nitrogen dioxide (NO2) emissions generated by
the engines of one catalytic chainsaw and two conventional chainsaws, of which one
is professional and the other amateur. Measurements were carried out under three
functional modes (infrequent accelerator use, use of quality oils, use of clean filters).
Measurements that were conducted under normal conditions were named „witness
measurements‟ and were used for future comparisons. Additionally, a set of
measurements for CΟ and ΝΟ2 emissions was collected under different operation
modes for all three types of saws (frequent accelerator use, use of low quality oils, use
of impure filters). Data collection was carried out in real conditions using a portable
gas detector. Average concentration values of CΟ and ΝΟ2 under normal conditions
for all three types of chainsaw found in the air of the operator‟s breathing zone were
88.32 ppm and 0.07 ppm respectively. Results show that CO concentrations exceed
the permissible exposure limit (50 ppm), whereas CO concentrations in excess of the
short-term exposure limit (300 ppm) were only found in the case of the amateur
chainsaw operated with low quality oils. These results are of use towards efforts to
reduce the CO and NO2 to the atmosphere.
Keywords: CO, NO2, greenhouse gasses, TLV
2
Introduction
In a work environment, low air quality due to hazardous emissions is one of
the elements which puts employees at high risk for illnesses through long-term
occupational exposure (Leszczyski 2014). In addition, exhaust emissions of logging
affects the environment and has major impacts on climate change. Climate change is
caused by the excessive levels of greenhouse gasses especially carbon, in the
atmosphere (Lijewski et al. 2013). Climate change has presented new challenges in
forest management (Keenan & Nitschke 2016). Logging operations emit greenhouse
gasses, hence creating a need for research on improved logging operations.
Merkisz et al. (2010) report that tests under actual operating conditions are one
of the most rigorous for measuring exhaust emissions generated by internal
combustion engines. In this way the operating conditions of the engine are taken
thoroughly into consideration (Lijewski et al. 2013). Additionally, the conditions of
the microenvironment in which a chainsaw is operating and which are constantly
changing can also be taken into consideration.
In this study exhaust emission measurements were performed while the
chainsaw operator was working under real conditions. Furthermore, scientific
research centers or legislative bodies consider introducing the on-road exhaust
emission testing of homologation procedures (Walsh 2011).
CO, hydrocarbons and nitric oxides constitute about 10% (6.2 and 1%
respectively) of chainsaw exhaust that are considered to be harmful to man. The
remaining 90% including nitrogen (N2), oxygen (O2), carbon dioxide (CO2) and water
(H2O) are not considered hazardous (Wójcik 2006).
Incomplete combustion of the engines leads to the creation of air pollutants
and particles. Two of the polluting combustion gases are CO as well as NO2. CO is a
colorless, odorless, and toxic gas used in numerous branches of industry or is
produced in the form of waste product. CO poisoning symptoms depend on its
concentration in the air, the period of activity and a person‟s work intensity. Short-
term exposures to concentrations of over 2181.5 ppm result in fainting and in case
of no fresh air (oxygen) access death within just a few minutes, due to brain hypoxia
(Ruth-Sahd et al. 2011).
In silviculture, CO is emitted by petrol powered internal combustion engines
such as heating devices at seed husking plants and retort furnaces used for wood coal
3
production. Exhaust emissions are frequently the topic of studies investigating the
impact of timber harvesting on the environment (Athanassiadis 2000). In a study by
Lijewski et al. (2013) it was found that emissions generated by two-stroke chainsaw
machines are ten times higher than those produced by other forest machinery such as
harvesters and forwarders. However, their concentrations in the forest environment
are quite low and do not exceed permissible exposure limits (Magagnotti et al. 2014;
Slaughter et al. 2004; Sowa et al. 2005).
The other harmful gas produced by two-stroke chainsaw engines is ΝΟ2.
Nitrogen monoxide (ΝΟ) at temperatures, higher than 1000oC (as in internal
combustion engines), is converted into ΝΟ2 and is part of the major pollutants
produced by two-stroke internal combustion engines such as chainsaw motors (other
pollutants of two-stroke engines include ΗC, CΟ, CΟ2 and particles) (Gentekakis
2003). Experiments on animals that were exposed to high concentrations of nitrogen
oxides (NOx), showed both reversible and irreversible injury to the lungs as well as
biochemical changes. Lower concentrations, with more prolonged durations of
exposure, led to tissue damage, obstruction of bronchioles and great susceptibility to
microbial inflammations of the respiratory system. In conclusion, higher oxide
concentrations are more detrimental to human and animal health compared with
prolonged exposure to lower concentrations (World Bank Group, 1998). Out of the
seven ΝΟx, three (Ν2Ο, ΝΟ, ΝΟ2) can be found in the atmosphere in high
concentrations of which only ΝΟ and ΝΟ2 are toxic.
Aim of this research
This study constitutes the second part of a research project investigating the
impact of chainsaw emissions on the environment and climate change. In detail:
1. The measurement of short-term concentrations of CO and ΝΟ2 is the 2nd
part of the project and aim of the current paper.
2. The measurement of short-term concentrations of ΝΟ and methane (CH4)
is the 1st part of the project (Dimou et al., 2018).
3. These measurements were carried out to investigate the use of chainsaws
for part-time at farm or urban green space maintenance and their impacts
on the environment.
4
Materials and methods
All measurements were collected under field conditions with the help of an
analyzer for the monitoring of exhaust pollutants (Dräger X-am 5000) emitted by
three chainsaws, namely a professional, a catalytic and an amateur. The exhaust gas
analyzer was portable and attached in the chainsaw operator‟s belt. Measurements
concerned CO and ΝΟ2 concentrations in the breathing zone of the chainsaw operator.
The three chainsaws that were used in the study were: a) a professional Stihl 361 MS,
b) an amateur Stihl 170 ΜS and c) a catalytic Stihl 170D (see Table 1 for the
characteristics of the three chainsaws). The term „breathing zone‟ refers to the 30cm
area immediately surrounding the operator‟s mouth and nose (Ojima 2012;
Leszczyski 2014). The measured values have been compared to the Threshold limit
value (TLV).
Table 1
Measurements were carried out for all three chainsaws under normal
conditions, i.e. with a regular to infrequent accelerator use, with good quality oils
(recommended and manufactured by a well-known company) and with clean filters.
These were benchmark measurements, used for future comparisons, and were named
witness measurements. Subsequently, for each of the three chainsaws separate
measurements of CΟ and ΝΟ2 emissions were performed with Χ‟2 = frequent
accelerator use, Χ‟3 = use of poor quality oils and Χ‟4 = impure filter, while the other
conditions remained normal (for Χ‟2 = use of good quality oils and clean filter, for
Χ‟3 = clean filter and infrequent use of accelerator and for Χ‟4 = good quality oils and
infrequent use of accelerator). The petrol that was used for the chainsaws was regular
unleaded with an octane number of 98.
Table 2 shows the chainsaw types that were used: Χ1= professional chainsaw,
Χ2= catalytic chainsaw and Χ3= amateur chainsaw, as well the operating parameters:
X’1= normal conditions, X’2= frequent accelerator use, X’3= poor quality oils, and
X’4 = impure filter. These conditions were repeated once for measurements Y1= CΟ,
and a second time for measurements Y2= NO2. In total, 1699 measurements were
carried out, of which 755 were for CO and another 892 for ΝΟ2 emissions.
Measurements were made in ppm (one part per million by volume in air - ml/m3).
5
Measurements of CO and NO2 gases have been taken during the cross-cutting
operations of Quercus petraea in an exposed yard (Figure 1). Measurements of both
CO and NO2 were taken simultaneously from the analyzer. Different operating
parameters per day have been applied separately for each chainsaw. Hence, gas
measurements for each type of chainsaw were completed in four days. Overall, the
total measurements, i.e. for each type of chainsaw and each operating parameter, were
collected within a duration of 12 days. The measurements were collected on-line in
the exhaust gas analyzer with the capability at the end of each experimental effort (i.e.
by measuring each type of chainsaw and operating parameters), the measurement data
to be transferred to a computer. Data were collected at the beginning of September
2018 at a mean temperature of Tmean = 23.6 0C while the minimum and maximum
temperatures were respectively TN = 17.20C and TX = 28.40C (HNMS 2018),
whereas longevity prevailed throughout the data collection period. Fuel wood has
remained in the exposed yard throughout the summer and was dry with a moisture
content of around 15%. The fuel wood was approximately 1.30-1.50m in length and
20-30cm thick. Cross cutting was made at a length size of 20-25cm. The total amount
of wood that was cut was 24m3.
Figure 1
Table 2
A statistical modeling approach was used to examine the potential effects of
the chainsaw type and operation type on the concentrations of CO and NO2 as they
were measured during the field conditions. Specifically, analysis of variance
(ANOVA) (Dobson and Barnett 2008) was chosen as the most suitable approach for
linking CO concentrations with the two factors under investigation. However,
concentrations of NO2 comprise a non-Gaussian distributed dataset including a large
number of zero values, hence making it not suitable for applying ANOVA. To respect
the nature of the specific dataset, a zero inflated Gaussian regression modeling was
applied (see, e.g., Lambert 1992; Malesios et al. 2014) to link the former factors of
chainsaw and operation type to the NO2 concentrations. In the following sub-sections,
the representations of the implemented statistical methods are analytically presented.
6
Two way analysis of variance
In order to examine the hypothesis that concentrations of CO are dependent on
the chainsaw and operation type, two way ANOVA was implemented. Let
i
a
be the
grouping variable which corresponds to the factor of chainsaw type with I levels (I =
3) and
j
the second independent variable which denotes the operation type with J
levels (J = 4), then the two way ANOVA can be written in generalized linear model
form as (Dobson and Barnett 2008):
1,... , 1,..., , 1,...,
ijk i j ijk
ij
ya
i I j J k n
 
 
 
(1)
where
ijk
y
denotes the values of the dependent variable,
the overall mean of
ijk
y
and
ijk
the error term. The total sample size is
ij
n
(
ij
n
= 755).
The appropriate criterion which is used in order to test if there are differences
concerning the dependent variable for each level of independent(s) is the F test. The
hypotheses which are tested assuming the first model are the following:
01
01
: ...
: ... I
J
H
H




(2)
Zero-inflated regression modeling
If
denotes the
thi
response of the
thk
independent variable of
concentration measurements of NO2 (i=1,2,…,892; k=1,2) and that
T
X
denotes the
)8922(
matrix comprising of the values of the independent variables, then the
regression-type zero inflated model fitted to the raw data of NO2 values is described
by the following equation:
 
βXt
ik
ikikik NeNy
22 ,0~;,~
(3)
where
ik
and
are the mean and variance of the dependent variables under a
Gaussian distribution. Finally,
 
t
k
,...,,21
β
are the regression coefficients of the
predictors, where
1
denotes the constant term and
k
,...,
2
are the coefficients for
the various levels of the two factors under investigation (k=1,2,…,5).
7
Results
Descriptive statistics
Table 3 below presents the descriptive statistics of CO and NO2 concentration
values in the overall data. The average CO concentration is 135.55 ppm, whereas the
average NO2 concentration is 7.09 ppm. However, it is also observed that the
measurements are extremely variable, as the standard deviation of the data is quite
large (184.31 ppm and 35.13 ppm for CO and NO2 concentrations, respectively).
Descriptive statistics for the data, broken down by the two factors of chainsaw
and operation type are presented in Table A1 in the Appendix.
Table 3
There are important differences in the average levels of the two pollutant
substances, however it is not easily identifiable if these large differences are due to
systematic variation in the levels of operation and chainsaw type or due to extreme
values. Subsequent analyses, attempt to answer this question, by use of statistical
inference in the form of regression-type modeling such as the two-way analysis of
variance and the zero-inflated regression.
The concentrations of CO in the breathing areas of workers during logging
operations are summarized (Figure A1 Appendix). The concentration values are
skewed, so the values were log-transformed to normalize their distribution (see Figure
A2). Logarithmic transformation of the CO concentration values results in the
normalization of the latter values, as is seen from inspection of Figure A2.
Figure A3 in the Appendix shows the CO concentrations broken down by the
type of chainsaw. The CO values measured with the amateur chainsaw are more
concentrated around zero when compared to the catalyst and professional chainsaws.
In figure A4 the average CO concentrations in terms of type of operation are shown.
The following bar charts (Figure 2) present the average log(CO)
concentrations in terms of the various levels of chainsaw type and operation type.
Figure 2
8
Tables 3 to 6 show the results of the two-way analysis of variance, in the form
of post-hoc tests. Specifically, the Scheffe, LSD and Bonferroni tests results are
included, in the form of mean differences between the various categories,
corresponding p-values and 95% confidence intervals.
Table 4 shows the post-hoc test results regarding the factor of chainsaw type.
That the only statistically significant difference in the levels of the log(CO)
concentrations is between the catalyst and the amateur chainsaws, with those
measured via the catalyst chainsaw showing increased levels of the pollutant.
According to the Scheffe test, mean difference between the catalyst and amateur
chainsaws is 0.249, with a corresponding p-value=0.043<0.05, indicating that the
difference is statistically significant at the 5% significance level (the 95% confidence
interval of the difference is 0.006-0.494).
Table 4
These results are summarized in Table A2 in the Appendix, where the two
subsets are distinguishing the levels of CO between the values of amateur and catalyst
chainsaws. Table 5 shows the post-hoc test results relating to the other factor of
operation type. Although the results are showing small differences between the three
tests, the main outcome is that the type of oil is statistically different from all other
three operation types with regard to the CO concentrations. Oil concentrations are
higher when compared to the other three types of operation. For a summary of the
post-hoc differentiation results, see Table A3 in the Appendix.
Table 5
Next, the effects of operation and chainsaw type on the concentration levels of
NO2 are investigated. Figure A5 in the Appendix, shows the concentrations of NO2
and log-transformed NO2. The data comprise of many excess zero values, making it
extremely difficult to transform the data for the residuals of NO2 to be normally
distributed, an assumption required for the robustness and validity of analysis of
variance method.
9
To perform an analysis on the particular dataset it is crucial to respect the
nature of the data, i.e. the inclusion of excess zeros along with the non-normality of
the observations. In order to do this, a zero inflated Gaussian regression model linking
the former values to the two factors of operation and chainsaw type was applied to the
NO2 concentrations.
The following bar charts (see Figure 3) present the average NO2
concentrations by the various levels of chainsaw and operation type. The figures
based on the raw data indicate that in terms of chainsaw type, the catalyst chainsaw
produced the highest levels of NO2 concentrations, whereas the descriptive results of
average concentrations show that the filter type has produced extremely high values
of NO2.
Figure 3
Τo generalize these descriptive results, a regression-type modeling based on
the zero inflated Gaussian distribution for the response variable of NO2 concentrations
was applied. The results of a regression-type modeling approach are presented below,
where the response is assumed to follow a zero-inflated (semi-) continuous
distribution.
Specifically, Table 6 presents the results of median parameter estimates for the
independent factors obtained by the fit of the zero inflated Gaussian regression model,
along with the corresponding significances in the form of p-values.
Table 6
Parameter estimates indicate that both factors are statistically significant
predictors of NO2. The results of parameter estimates indicate that for the different
levels of the covariate of chainsaw type, it is observed that under the catalyst
chainsaw, concentration measurements of NO2 are higher, in comparison to the other
two types of chainsaws used (b = 121.9, p-value<0.05). There are also statistically
significant differences among the various types of operations with regard to NO2
concentrations. According to the results of Table 6, the NO2 concentrations are higher
for the filter operation type in comparison to all other operations (i.e. witness,
frequent acceleration and oil), since all operation type parameters are negative and
10
statistically significant in comparison to the reference level category of filter (p-
value<0.001), indicating that their operation reduces the NO2 concentrations.
The visual representation concerning the interaction between the
concentrations of CO for operation and chainsaw type, depicted in Figure 4b, assists
in the interpretations of our results. Measurements collected by the oil operation type
are always higher, independent of the chainsaw type used. The acceleration operation
type is shown to be dependent on the chainsaw type, as the CO concentrations are
significantly decreasing when using an amateur chainsaw versus a catalyst. This is
also true when using the witness operation type. The catalyst chainsaw used in the
acceleration operation has significant problems, in terms of the CO concentrations,
since the combination of catalyst chainsaw with an acceleration operation produces
the highest CO concentrations.
Figure 4 a,b
As it is illustrated in Figure 4a, CO emissions for the professional and
catalytic chainsaw for the three operating parameters (frequent accelerator use, use of
poor quality of oils and impure filter) are below the TLV. This value is slightly
exceeded (301.12 ppm) in the case of the amateur saw when used with low quality
oils. Τhe results show excess of Permissible Exposure Limit (50 ppm) or, the time
weighted average permissible exposure limit, which is also seen in the study by Sowa
and Leszczyṅski (2014).
Figure 5 a,b
Figure 5b compares the concentration levels of NO2 considering the
interaction effects of both operation type and type of chainsaw.
All three types of chainsaw seem to be affected similarly by the operation
type, in terms of the NO2 pollution concentrations. In general, the filter operation type
increases the concentration levels for all three types of chainsaw. The catalytic
chainsaw, as seen in Figure 5b, causes higher NO2 concentrations in all cases under
investigation. Note that for ΝΟ2 the threshold limit values are 5 ppm for 8-hour daily
work and short-term exposure (Figure 5a). ΝΟ2 emissions are below the TLV for all
11
chainsaw types (professional, catalytic, amateur) and the three different functional
modes (frequent accelerator use, low quality oils and impure filters) (Figure 5a).
Discussion
Pollutants emitted by chainsaws during forest operations and logging can
cause deterioration of the natural environment by adding to the greenhouse effect and
enhancing health hazards (Athanassiadis 2000).
The study of exhaust emissions produced by forestry machinery shows that
CO emission is 10 times higher in the case of two-stroke chainsaws than in the case of
harvesters or forwarders (Lijewski 2013).
The exposure limits for harmful or hazardous substances in the air have been
defined in employment protection regulations (Leszczyski 2014). Greek regulations,
set by the Hellenic Institute for Occupational Health and Safety, concerning threshold
limit values for chemical substances specify that the CO permissible exposure limit
must not be higher than 50 ppm in the case of the 8-h time-weighted average
permissible exposure limit (TWAEL) and 300 ppm in the case of the 15-min short-
term exposure limit (STEL). Exceeding the 15-minute short-term exposure limit must
not occur more frequently than twice per work shift or once every hour (Leszczyski
2014).
Threshold limit value is determined in Greece by two Presidential Decrees
(P.D. 338/2001 and P.D. 339/2001), which define it as the limit of an employee‟s
exposure to a chemical agent, measured in the air of his/her breathing zone, that
should not be exceeded during any kind of 8-hour daily work and forty-hour weekly
work (Daikou & Dontas 2013). The current TLV is listed at 300ppm.
Another recent major development in the chainsaw sector is that of battery
powered chainsaws that ultimately eliminate the impact of exhaust gases on humans
and the environment. Today they represent a large share of the chain saw market.
Their advantages include, in addition to eliminating exhaust gases, their lower weight
as well as less vibration and noise during operation, compared to conventional saws
(Colantoni et al. 2016).
Also another alternative for the use of a chainsaw without any environmental
impact is that of electric chain saws. Of course, however, they can mainly be used for
home use because they require a power supply. They could, however, be used in
house firewood operations. In the market, electric chainsaws can be found under
12
specifications of 45cm length and a power of 2.5KW which are capable of most wood
cutting operations, whereas lithium-ion chainsaws can be used in tree trunks and tree
treatments as well as part-time at farm operations (Colantoni et al. 2016).
For chainsaws using alternative energy sources, such as the electric and the
battery chainsaws, the average acceleration is lower than the one measured in the
endothermic chainsaws (Neri et al. 2018; Poje et al. 2018). This results in added value
of the former chainsaws, since that in general in the endothermic chainsaws the
increase in exhaust emissions is influenced by the use of rich fuel mixtures (Wójcik &
Skarzyński 2006).
In the present study it was shown that the increase in CO emissions (Figure 4)
during intense use of acceleration affects all chainsaws, but mainly the catalytic and
semi-professional chainsaws. Also, it has been shown that in the professional
chainsaw case, emissions in NO2 are increased for the same reasons as above (Figure
4). Most of research on the endothermic chainsaw emissions concentrate on CO and
hydrocarbons emissions and are less focused on NO2 emissions. Wójcik & Skarżyński
(2006) report an increase in CO for endothermic chainsaws of approximately 7-8%,
which can reach up to 8-9% with frequent acceleration operation. The highest
proportion of CO in this case according to Wójcik & Skarżyński (2006) is due to the
reduced amount of oxygen in the gas-fuel mixture.
The reduction of CO exhaust emissions, besides the controlled use of
acceleration, can be achieved by introducing a proper adjustment of the chain saw
carburetor (Emmerich & Burger 1993; Róński & Jabłoński; Wójcik 2003). Wójcik &
Skarżyński (2006) also report the positive effects of the clean filter on the reduction of
CO emissions, which has been also verified by the present study (Figure 4).
An equally important source of exhaust gases is through the fuel vapor from
the carburetor, i.e. the fuel tank, resulting from leakages of the fuel system into the
atmosphere and subsequently the creation of nitrogen compounds (nitrates, aldehydes,
peroxides and ozone) when combined with atmospheric oxygen, contributing thus to
the creation of the photochemical cloud (see, e.g., Różański & Jabloński 2001).
The adverse effect of fumes can be reduced by the use of special fuels, free of
polycyclic hydrocarbons, such as the Alkylate fuel (Wójcik & Skarżyński 2006). In
the present work, Alkylate fuels have not been examined because they are generally
not used in Greece, however according to the authors opinion, the focus in Greece
13
both with regard to research efforts as well as in practice, must concentrate towards a
shift to Alkylate fuel.
According to Neri et al. (2018) there were statistically significant differences
in the inhalation exposure to exhaust gas (PAHs) and BTEX (i.e. benzene, toluene,
ethylbenzene and total xylenes) when using different fuel types. The exposure
according to Neri et al. (2018) due to inhalation in PAHs and BTEX was generally
lower when using modern alkylate fuels as compared to the traditional oil and lead-
free petrol mixture.
Conclusions
The professional chainsaw
Generally speaking, a professional saw causes lower CO emissions than a
catalytic saw and higher CO concentrations in comparison with an amateur saw under
normal operating conditions and frequent accelerator use (Fig. 4b). The catalyst saw
under the acceleration operation has been shown to produce high CO emissions. With
regard to ΝΟ2 emissions, the amounts that it generates are generally less than the
catalytic and slightly higher than the amateur saw (Figure 5b).
The catalytic chainsaw
The catalytic chainsaw generates the highest amounts of ΝΟ2 emissions
(Figure 5b). CO concentrations are also higher in comparison with the professional
and amateur saws. When the catalytic saw is operated with frequent accelerator use, it
releases higher amounts of CO than the other two saws. However, when it is used
with impure filters it produces less CO than the other two saws, a value which,
nevertheless, is fairly high (Figure 4b).
The amateur chainsaw
Releases approximately the same amounts of ΝΟ2 gases (Figure 5b) as a
professional saw. CO concentrations are relatively low when the saw is operated with
frequent accelerator use. Bad quality oils and impure filters considerably affect its
performance (Figure 4b).
Gas emissions can be reduced by applying special fuels without polycyclic
hydrocarbons or introducing a suitable regulation of the chain saw carburetor. This
would facilitates the reduction of CO emission (Emmerich & Burger 1993; Różański
& Jabloński 2001; Wójcik 2002).
14
Τhe amateur chainsaw has proved to be safer and less harmful to the
environment in terms of NO2 emissions however, the use of low quality oils is not
recommended as it results in higher NO2 concentrations. On the other hand, a
professional saw is less harmful as far as CO emissions are concerned. Finally, the
catalytic saw emitted the highest concentrations of NO2, when used under an
accelerated operation.
The use of low quality oils is the factor that most significantly affects the
emission of the pollutants under investigation regardless of the type of chainsaw. The
second most important factor that determines CO concentrations for all three saw
types is the use of impure filters. The operation of the chainsaw with frequent
accelerator use is affected by the saw type with the catalytic saw producing the
highest CO concentrations (Figure 4b).
According to the results of this study, the use of a conventional chainsaw is
highly recommended. Modern amateur saws have excellent performance; but they
cannot be compared with professional ones, since they are considered less user-
friendly and less environmentally friendly as they release higher amounts of
emissions when used with impure filters.
For all three chainsaw types used and under all the operating conditions, the
results show excess of the CO Time-Weighted Average Permissible Exposure Limit
(50 ppm), which was also seen in the study by Leszczyski (2014). The amateur
chainsaw produces the lowest CO emissions under all operating conditions except
when operated with frequent accelerator use.
The results that the use of the catalytic saw is not found to be more effective in
relation to the release of CO and NO2 pollutants are in agreement with another study
by Dimou et al. (2018) clearly show. When the professional saw is used, its
maintenance and way of operation are of paramount importance. This means that its
filter should be frequently cleaned according to the manufacturer specifications and
recommended using oils; low quality oils must be avoided (Dimou et al. 2018).
The wind variation accounts for much of the wide variation in measured
concentrations at the breathing zone samplers. In the absence of other information it
could be assumed that still air would result in the highest breathing zone
concentrations. Nilsson et al. (1987) comment that their survey of operators showed
that the worst subjective symptoms of exposure were associated with thick forest,
calm weather and deep snow.
15
According to the work by Wójcik and Skarżyński (2006), the threat caused by
CO can be multiplied by: unfavorable wind direction and speed, as well as its lack,
local conditions, compaction of the stand, chainsaw poor technical conditions, usage
of too rich fuel mixtures, and the maladjustment of the carburetor.
The outcomes of the present study can be of use on giving guidance on the use
of greener chainsaw operations for reducing hazardous emissions to the atmosphere
during logging operations.
References
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18
APPENDIX
Table A1. Descriptive statistics for the CO and NO2 concentrations, broken down by
chainsaw and operation type
Measured
gases(ppm)
Min.
Max.
Mean
media
n
Std.
Deviatio
n
N
CO
catalyst
6
1238
152.43
107
161.49
204
professional
6
285
114.75
85
107.18
274
amateur
0
1860
143.70
60
248.09
277
witness
6
1238
88.23
59
112.21
204
acceleration
0
690
107.18
58
123.45
205
oil
6
1860
221.69
144
275.42
209
filter
6
585
117.05
74
119.74
137
NO2
catalyst
0
380
18.57
0.1
55.12
338
professional
0
0.3
0.06
0
0.104
274
amateur
0
0.4
0.03
0
0.082
277
witness
0
0.3
0.07
0
0.101
204
acceleration
0
0.3
0.06
0
0.095
205
oil
0
0.4
0.04
0
0.091
209
filter
0
380
23.13
0
60.71
271
Figure A1. Histogram of CO concentration in breathing areas of workers during
logging operations
19
Figure A2. Histogram of log (CO) in breathing areas of workers during logging
operations
Figure A3. Histogram of CO (ppm) concentration in breathing areas of workers by
type of chainsaw
20
Figure A4. Histogram of CO (ppm) concentration in breathing areas of workers by
type of operation
Table Α2. Subsets derived from Post-hoc test of Scheffe by chainsaw type
Post-hoc
test
Chainsaw
type
Subset
1
2
Scheffe
amateur
4.183
professional
4.319
4.319
catalyst
4.433
Table Α3. Subsets derived from Post-hoc test of Scheffe by operation type
Post-hoc
test
Operation_type
Subset
1
2
Scheffe
witness
4.000
acceleration
4.071
filter
4.282
oil
4.831
21
Table 1. Characteristics of the chainsaws used in the study
Figure A5. Histogram of NO2 (ppm) and log(NO2) concentration in breathing areas
of workers during logging operations
Brand
Model
Engine
size (cm3)
Power
(KW/CV)
Capacity (l)
Weight
(empty KG)
Tank
volume
Oil Tank
volume
Stihl
MS 361
59.0
3.4/4.6
0.68
0.325
5.6
Stihl
MS 170
30.1
1.2/1.6
0.25
0.145
4.1
Stihl
D 170
30.1
1.2/1.6
0.25
0.145
4.2
22
Table 2. Measurement conditions of (Y1= CO) and (Y2= NO2) emissions produced by
a professional, a catalytic and an amateur chainsaw
Total measurements Y1= CO: 755
Total measurements Y2= NO2: 892
Type of chainsaw
Operating
parameters
X1= Professional
Χ2= Catalytic
Χ3= Amateur
X1 = Normal
conditions
ΧX‟1,1 = Professional
under normal conditions
ΧX‟2,1 = Catalytic under
normal conditions
ΧX‟3,1 = Amateur under
normal conditions
X2=Frequent
accelerator
ΧX‟1,2 = Professional
with frequent accelerator
ΧX‟2,2 = Catalytic with
frequent accelerator
ΧX‟3,2 = Amateur with
frequent accelerator
X’3=Poor quality oils
ΧX‟1,3 = Professional
with poor quality oil
ΧX‟2,3 = Catalytic with
poor quality oil
ΧX‟3,3 = Amateur with
poor quality oil
X’4=Impure filter
ΧX‟1,4= Professional
with impure filter
ΧX‟2,4 = Catalytic with
impure filter
ΧX‟3,4 = Amateur with
impure filter
23
Table 3. Descriptive statistics for the CO and NO2 concentration (ppm) in breathing
areas during logging operations
Measured
gases
(ppm)
Minimum
Maximum
Mean
Std.
Deviation
N
CO
0
1860
135.55
184.31
755
NO2
0
380
7.09
35.13
892
24
Table 4. Post-hoc tests from Analysis of variance for the differences between
chainsaw types for log(CO) concentration
Post Hoc
test
Chainsaw type
Mean
Difference
p-value
95% Confidence Interval
Lower
Bound
Upper
Bound
Scheffe
catalyst
professional
0.114
n.s.
-0.131
0.358
amateur
0.249*
0.043
0.006
0.494
professional
catalyst
-0.114
n.s.
-0.358
0.131
amateur
0.136
n.s.
-0.089
0.362
amateur
catalyst
-0.249*
0.043
-0.494
-0.006
professional
-0.136
n.s.
-0.362
0.089
LSD
catalyst
professional
0.114
n.s.
-0.082
0.309
amateur
0.249*
0.012
0.054
0.445
professional
catalyst
-0.114
n.s.
-0.309
0.082
amateur
0.136
n.s.
-0.044
0.317
amateur
catalyst
-0.249*
0.012
-0.445
-0.054
professional
-0.136
n.s.
-0.317
0.044
Bonferroni
catalyst
professional
0.114
n.s.
-0.125
0.353
amateur
0.249*
0.037
0.011
0.489
professional
catalyst
-0.114
n.s.
-0.353
0.125
amateur
0.136
n.s.
-0.084
0.357
amateur
catalyst
-0.249*
0.037
-0.489
-0.011
professional
-0.136
n.s.
-0.357
0.084
n.s.: non-significant; *significant at the 5% significance level
25
Table 5. Post-Hoc tests from Analysis of variance for the differences between
operation types for log(CO) concentration
n.s.: non-significant; *significant at the 5% significance level
Post Hoc test
Operation type
Mean
Difference
p-value
95% Confidence
Interval
Lower
Bound
Upper
Bound
Scheffe
witness
acceleration
-0.070
n.s.
-0.369
0.228
oil
-0.830*
<0.001
-1.127
-0.533
filter
-0.282
n.s.
-0.615
0.051
acceleration
witness
0.070
n.s.
-0.228
0.369
oil
-0.760*
<0.001
-1.057
-0.462
filter
-0.211
n.s.
-0.545
0.122
oil
witness
0.830*
<0.001
0.533
1.127
acceleration
0.760*
<0.001
0.462
1.057
filter
0.548*
<0.001
0.216
0.880
filter
witness
0.282
n.s.
-0.051
0.615
acceleration
0.211
n.s.
-0.122
0.545
oil
-0.548*
<0.001
-0.880
-0.216
LSD
witness
acceleration
-0.070
n.s.
-0.280
0.139
oil
-0.830*
<0.001
-1.038
-0.622
filter
-0.282*
0.018
-0.515
-0.048
acceleration
witness
0.070
n.s.
-0.139
0.280
oil
-0.760*
<0.001
-0.968
-0.551
filter
-0.211
n.s.
-0.445
0.022
oil
witness
0.830*
<0.001
0.622
1.038
acceleration
0.760*
<0.001
0.551
0.968
filter
0.548*
<0.001
0.316
0.781
filter
witness
0.282*
0.018
0.048
0.515
acceleration
0.211
n.s.
-0.022
0.445
oil
-0.548*
<0.001
-0.781
-0.316
Bonferroni
witness
acceleration
-0.070
n.s.
-0.352
0.212
oil
-0.830*
<0.001
-1.110
-0.549
filter
-0.281
n.s.
-0.596
0.032
acceleration
witness
0.070
n.s.
-0.212
0.352
oil
-0.760*
<0.001
-1.040
-0.479
filter
-0.211
n.s.
-0.526
0.103
oil
witness
0.830*
<0.001
0.549
1.110
acceleration
0.760*
<0.001
0.479
1.040
filter
0.548*
<0.001
0.235
0.861
filter
witness
0.281
n.s.
-0.032
0.596
acceleration
0.211
n.s.
-0.103
0.526
oil
-0.548*
<0.001
-0.861
-0.235
26
Table 6. Parameter estimates of the zero inflated regression model and corresponding
significances
n.s.: non-significant
Covariate
Median
p-value
Constant
15.47
<0.001
Chainsaw type (reference category: amateur)
Catalyst
15.39
<0.001
Professional
-0.02
n.s.
Operation type (reference category: filter)
Witness
-20.45
<0.001
Acceleration
-20.51
<0.001
Oil
-20.43
<0.001
deviance
7,486
27
FIGURES
Figure 1
Figure 2
Figure 3
28
Figure 4a,b
Figure 5a,b
29
Figure 1. Logging of Quercus petraea in an exposed yard
Figure 2. Bar chart of the average ln (CO) concentration (ppm) by type of chainsaw
and operation
Figure 3. Bar chart of the average NO2 concentration (ppm) by type of chainsaw and
operation
Figure 4 a,b. (a) Concentration of CΟ in ppm (a raw data values) by operation and
chainsaw type (b) Line plot of average CO concentration by operation and chainsaw
type (log-transformed values)
Figure 5 a,b. (a) Concentration of NO2 in ppm (a raw data values) by operation and
chainsaw type (b) Line plot of average NO2 concentration by operation and chainsaw
type (log-transformed values)
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Continuing to emphasize numerical and graphical methods, An Introduction to Generalized Linear Models, Third Edition provides a cohesive framework for statistical modeling. This new edition of a bestseller has been updated with Stata, R, and WinBUGS code as well as three new chapters on Bayesian analysis. Like its predecessor, this edition presents the theoretical background of generalized linear models (GLMs) before focusing on methods for analyzing particular kinds of data. It covers normal, Poisson, and binomial distributions; linear regression models; classical estimation and model fitting methods; and frequentist methods of statistical inference. After forming this foundation, the authors explore multiple linear regression, analysis of variance (ANOVA), logistic regression, log-linear models, survival analysis, multilevel modeling, Bayesian models, and Markov chain Monte Carlo (MCMC) methods. Using popular statistical software programs, this concise and accessible text illustrates practical approaches to estimation, model fitting, and model comparisons. It includes examples and exercises with complete data sets for nearly all the models covered.
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